1. Field of the Invention
The present invention generally relates to a technical filed of data transmission. More particularly, the present invention relates to a transmission parameter control apparatus for performing data transmission using RTP (Real-time transport protocol) and RTCP (RTP control protocol) on a transmission route including a wireless section in a part of the transmission route.
2. Description of the Related Art
The RTP and/or the RTCP are protocols for transmitting real-time media such as voice signals and video signals. The real-time media are generated from data that are generated continuously in terms of time. For reproducing the data in a receiving side, it is necessary to reproduce the data at time intervals the same as those in a sending side (a side in which the data is generated). Therefore, for transmitting the real-time media, qualities (quality parameters) such as packet transfer delay time, jitter indicating fluctuations of the packet transfer delay time, and packet discarding ratio are especially important.
Japanese Laid-Open Patent Application No.2002-204278 (Patent document 1) discloses a technology for performing bit-rate adjustment and error tolerance level change for transmission data in the sending side according to a state of a transmission route, based on the jitter and the packet loss ratio (discard ratio) obtained from the receiving side. According to this method, since the transmission method can be adjusted so that proper data transmission is performed for the receiving side, high quality transmission can be performed for real-time media data. In the same way, in a technology disclosed in Japanese Laid-Open Patent Application No. 2002-325095 (patent document 2), a transmission data rate (bandwidth) is properly set according to a status in the receiving side.
[Patent document 1] Japanese Laid-Open Patent Application No.2002-204278
[Patent document 2] Japanese Laid-Open Patent Application No. 2002-325095